Overview

Overview

Perciforms, or perch-like fish, can be considered the dominant vertebrates in the world’s oceans.(1) This not-clearly-delimited taxonomic group (2,3) forms the largest order of fish,(1,2,4,5) and indeed the largest order of vertebrates;(1,4) with over 10,000 species,(1,2,3,4) ranging from Arctic to Antarctic waters,(2,3) the perciforms comprise at least a third of all fish species.(2,4) While perciforms live in a variety of habitats, from freshwater rivers, lakes, and ponds(2,3,4,5) to the far depths of the oceans,(2,3,4) the greatest array of species can be found in marine environments close to shores,(3,5) especially in coral reefs.(4) They vary widely in size (anywhere from 1.2 centimeters to 3.3 meters long), shape, color, feeding behavior, and breeding and migration behavior.(3) In fact, this order of fish is so diverse that the families contained within it may not even all stem from a common evolutionary ancestor.(2,3,5) Still, there are some important characteristics that most perciforms share. These include, among others, pectoral fins on the sides;(4) spines on the dorsal and anal fins, probably for self-defense;(2,3) pelvic fins on the abdomen with one spine and up to five soft rays;(2,3,4) dorsal and anal fins that are detached from the caudal (tail) fin,(2,3) which has fewer than eighteen principal rays;(4) and a jaw that can be thrust outward to suck food into the mouth.(3) Perciforms occupy important positions in ecosystems, serving as both predators and prey and frequently taking part in mutually-beneficial relationships with other species, as in the case of the cleaner fish which eat parasites off of larger fish.(3) For thousands of years, perciforms have also been highly significant for humans, who make use of such perciforms as tuna, mackerel, bass, and many others as major food sources(3)—so much so that some perciforms are now seriously threatened by over-fishing.(3,4) Today many beautiful perciforms are also popular as aquarium fish.(3)